This invention relates to a piston machine which can operate either as an engine or as a compressor.
An example of a piston machine of the prior art, in which the working medium can be conducted through the crankcase, is a two-stroke radial engine. The starting point of the invention is not, however, the provision of an improved internal combustion engine. The objective is rather to provide an improved working machine which can also be used as an engine.
A known example of such a working machine is a reciprocating piston compressor. The latter device cannot, however, be operated as a working machine without having to make extensive structural modifications to the overall construction of the compressor. Furthermore, compressors usually operate with a valve control. A valve control is prone to wear and, due to the masses moved, permits only limited speeds of rotation. Moreover, all known working machines operating with a valve control have a dead space, inherent in their construction, wherever valves or valve plates seal the piston working chamber, and the machines are inherently designed so that they act as check valves. The dead or waste space reduces the efficiency of the machine because the working medium compressed therein always remains in the working chamber, i.e. the chamber is never completely emptied. Clearly, the latter problem reduces the efficiency of the machine.
Reciprocating piston compressors, which today are used in refrigeration equipment, have the disadvantage that great damage is caused if liquid forms in the refrigerant and enters the compressor. Usually, the action of the liquid damages the valve plates. To avoid this and other disadvantages, the practice is now to use plate compressors, i.e. compressors operating only by the displacement principle. However, these also have disadvantages, i.e. greater wear at the discs due to strong area pressure between the discs and the housing inner wall at the sealing points. Furthermore, swashplate compressors have already been used but these have the disadvantage that high frictional losses occur therein and this also leads to poor efficiency.
All rotary piston working machines operating by the displacement principle can also be operated as engines. It is, for example, known to cause disc compressors to operate as disc motors (e.g. in pneumatic tools, as drive motors). However, the disadvantages which such machines have as working machines are still present when they operate as engines or prime movers. Moreover, such engines have a very high consumption of working medium, and for this reason, they also have poor efficiency.
Finally, the piston machines of the prior art have poor size/power ratios.